Apparatus and method for making folding plastic containers



May 22. 1956 s. BRIGHT, JR

APPARATUS AND METHOD FOR MAKING FOLDING PLASTIC CONTAINERS 2 Sheets-Shem 1 Filed May 9, 1952 A TTORNE YS.

May 22, 1956 s. BRIGHT, JR 2,746,360

APPARATUS AND METHOD FOR MAKING FOLDING PLASTIC CONTAINERS Filed May 9, 1952 2 Sheets-$hee 2 BY Wd-PM A T TORNE Y5 APPARATUS AND METHOD FOR MAKING V vFOLDING PLASTIC CONTAINERS 3 Stanley Bright, Jr., Haverford, Pa., assignor to Truth Bright Page, Inc., Pauli, Pa., a corporation of Pennsyl vania I Application May 9, 1952,'Serial No. 287,064

1:0 Claims. (Cl. 93-.36)

' This invention relates to apparatus and method'jfor making folding plastic containers, and furtherrelatesto apparatus and method for making a seamless plastic folding container blank. More particularly, the invention re,- lates to a method which comprises extruding a plastic tube *of enclosed cross section, folding the tube substantially The fabrication of containers by this method involves not. Q only an extra operation but also results in a visible line along the joining element.

i United States Patent pounded into the particular plastic tobe extruded; It is also possible to include minor amounts of solvent in the plastic to facilitate extrusion. In practicing the extrusion step of my invention, the plastic material may be forced;

. ably circular in shape and1produceacontinuous hollow plastic tube. Plastic structures having closed cross sections of any kind are referred to herein as tubes. In

- carrying out the extrusion step of my method, the extrusion dies may be heated to attain preferred extrusion of some plastic materials, and to drive off any solvent that may have been included in the original plastic stock, but

v It is accordingly an object of this invention to provide I a rapid and economical method of making. a'plastic fold ing container having no adhesive seams. It is another object of my invention to make a strong, durable plastic folding container blank in the form of a flat double sheet for convenience and economy in shipping. Other objects and means for carrying them into eifect will'appear here! inafter and in the drawings, in which:

Fig. 1 is a bottom view in perspective ofthe upper or male'cutting and scoring die used inmyprocess. I

Fig. 2 is a top view in perspective 'of the mandrel used in my process with a plastic blank inserted thereon.

Fig. 3 is a bottom view in perspective of the mandrel and blank with a portion broken away and showing in section constructional details thereof.

Fig. 4 is a top view in perspective of the lower or female cutting and scoring die used in my process.

' "Fig. 5 is a top view in perspective of the mandrel and blank showing the final cutting operation of my process.

. Fig. 6 is a perspective View .of a plastic f olding com tainerblank produced by my process.

In practicing the method which constitutes invention, a suitable transparent plastic material is first extruded through a set of dies or other extruding means to forma hollowplastic tube. For purposes of the first step, the plastic may consist of a transparent organic thermoplastic or thermo setting material such as. cellulose acetate, polyethylene resins, methyl methacrylate "resins, vinyl acetate vinyl' chloride copoly mers, vinylidene chloride copolymers, or other plastics which become partially fiuid under pressure and which revert to an inflexible physical state" when the pressure is released. It will be understood that a'particular plastic"material may be--'preferred in certain cases in view of the desired characteristics of the finished container for particular purposes.

The extrusion of several varieties of plastics may. be

, .accomplishedat ordinary temperatures by applicationof pressure against the bulk plastic material to force it 40 and pad 45 of die 38 is opposed and absorbed by pads 33 and 34 of die 26; the force exerted against said mandrel through adie. In some cases, however, it is found desirable to enhance the plasticityof the plastic and for this in many instances the extrusion maybe accomplished without heating. i a

After extrusion, the hollow plastic tube is flattened in any manner well known in the art to form a pair of substantially fiat, oppositely positioned plastic walls. From the fiatt'ened'tube are cut blanks 10 (Fig. 2) of a predetermined size having longitudinal fold lines 11 and 12. Blank 10 is then fitted over a flat rigid mandrel13, as shown in Figs. 2 and 3, by sliding said blank over end 14 of said mandrel. i V

Mandrel 13 is formed preferably of hardened steel and has a relatively narrow tongue element 13a which merges into a somewhat wider head element 13b. Slopingknife edges 15 join the outer edges of the head element 131; withthe outer edges to tongue element 13a. upper face of tongue element 13a of mandrel 13, as shown in Fig. 2, are raised scoring ridges 16, 17 and 18. Mounted on the lower face of tongue element 13a of mandrl113, as shown in Fig. 3, are raised scoringridges 19,20, 21,

22, 23, and 24 and mounted on the lower face of the head 1 element 13b thereof is a raised scoring ridge 25.

The cutting and scoring operation on the upper wall of die 38 having cutting blades 39, 40, 41 and 42 and re-" silient pads 43, 44, 45, 46, 47, 48, and 49, likewise preferably made of hard rubber, mounted thereon.

The cutting and scoring operations proceed as follows. The flattened blank 10 is inserted on tongue 13a of mandreI 13 and advanced onto head 13b as shown in 2.. As the blank 10 advances onto head 13b, knife edges 15' on the mandrel 13 sever the blank 10 along folds 11 and 12. The extent of advance of the blank 10 onto mandrel head 13b and hence the extent to which the blank 10 is severed along folds 11 and 12 islimited and predeter-i mined by the desired size of the container blank to be produced.

of blank 10 thereon.

positioned below die 26 and on die 38 by means of brackets 50, adapted to receive mandrel head 13b and studs 51, adapted to hold in proper alignment'mandrel tongue element 13a. Thereupon, dies 26 and 38 are brought toward each other (by means of a platen press, for example) and are forcibly and simultaneously driven against the opposite walls and faces respectively of blank 10 and mandrel 13. The force exerted by one die against predetermined cutting and scoring lines. Specifically, the

force exerted against mandrel 13 by cutting blades 39 and Patented May 22,1956:

Mounted in the If desired, indicating marks maybe formed on mandrel head 13b to show the proper extent of advance 7 After blank 10 has been properly} inserted upon mandrel 13, the mandrel is then correctly.

3 by cutting blades27, 28 and 39 of die26 is opposed and absorbedby' pads 43' and 44 of die' 38'; the force exerted against said mandrel by cuttiiig blades 41 and 42 and pad 48 of die 38 is opposed and. absorbed by. pads 36and..3.7 of die- 26; the force exerted. against. said mandrel by cutting blades 30,, 31 and 32. of die 26 is opposed and absorbedby pads. 47' and 49 of die 38; and thev force exerted.

against said'mandrel by pad 35- on. die. 26 is opposed and absorbed by pad 46 on .die 33.

It. will be observed that the contacting of the opposed dies 26 and 38 forcibly against. blank 1.0 and mandrel 13 wiIl, force the various cutting blades, which preferably are. made of hardened steel or other suitable cutting metal, completely through the plastic walls of. the. blank llland forcibly against the unyielding, rigid surfaces of said mandrel. 'S'pecifically, cutting blades. 27,23, 29, 3d, 31 and 32 of die. 26 will respectively penetrate and sever the upper wall of blank along lines 27a, 28a, 29a, 30a, 3121 and 32a (see Fig. 2) and, similarly, cutting blades 39, 40, 41 and 42 of die 38 will penetrate and sever respectively the lower wall of blank 10 along lines 39a, 40a, 41a and 42a (see Fig. 3)

Itwill be further observed that pads. 34, 35 and. 36 are mounted upon die 26 so as to be directly andrespectivelyabove scoring ridges 16, 17 and 18 on mandrel 13 when said mandrel is properly positioned by brackets 54 and.

studs 51. Accordingly, when die 26 is contacted. forcibly against mandrel 13 and blank 10, pads 34, 35 and 3.6 are pressed against that part of the upper plastic wallof blank 10 which is directly above scoring ridges 16, 17 and 18, thus. stretching the plastic wall to form. fold lines. 34a, 35a and 36a and rendering said plastic wall foldable along said fold lines. Likewise pads 43, 44, 45', 46, 47, 4S and 49 are mounted upon die 38 so as to be directly and respectively below scoring ridges 25, 20, 19, 21, 23,22 and 24 on mandrel 13 when said mandrel is. properly positioned by brackets 50 and studs 51. When die 38 is contacted forcibly against mandrel 13 and blank 10, pads 43,.

10. The yielding property of said pads permits bending of the plastic walls of the blank along the fold lines thereof rather than resulting in a parting of the. plasticalong said lines.

Upon completion of the cutting. and scoringoperations just described, flaps 52, 53 and 54 of blank 10 will be completely formed, but flaps 55, 56 and 57 will not be fully formed since those portions of fold lines 11 and 12 which define. the. side edges of said flaps have not been severed. The completion of the formation of blank 10 may be accomplished while said blank is still inserted upon mandrel 13, as shown in Fig. 5. A knife edge 58 (shown in dashed lines) is inserted under oneof the walls of blank 10 and moved along the surface of mandrel 13 so as to sever fold line 11 between points 59 and 60 of said line and. so as to sever fold line 12 between points 61 and 62 of said line. Thereupon the cuttings are separated from the blankand the finished blank 10 removed from mandrel 13 and assembled as shown in Fig. 6.

It. is often relatively difiicult with some extrudedpla-stic materials, particularly where the plastic walls are relatively thick, to fold. the material inward when it has been scored. on the outside. The provision of a mandrel of the type herein shown and described, having scoring ridges mounted thereon, overcomes this difficulty since the fold lines. formed. by said scoring ridges are formed on the 1n-- sideof. the. walls of the plastic blank, thus greatly facilitating, the final; assembly of the plastic blank.

It will be apparent that my new apparatus and method maybe practiced in connection with any suitable plastic material that may be selected by a person skilled in the field of plastics. The invention may similarly be adopted to the manufacture of containers of widely varying shape and designs. It is to be distinctly understood that the apparatus and method herewith shown and described is to be taken as a preferred" example of the same, and that various changes in the shape, size and arrangement and utilization of the parts may. be. resorted to without departing from the. spirit of the invention or scope of the claims.

This application is a continuation in part of my previous application filed on April 22, 1:949, and bearing Serial No. 88,943, now U. 8;. Patent No. 2,712,777.

Having thus described the invention, I claim:

1. A method of making a seamless plastic folding container blank from an extruded plastic tube comprising flattening said. tube. to form folded side. edges, cutting a blank from said flattened tube,, inserting. a Hat rigid mandrel having scoring ridges mounted thereon between the walls of said blank, contactingcutting knives to each wall of said blank under suflicient pressure to cut completely through said walls alongpredetermined' cutting lines, con tacting resilient pads. forcibly against said walls. to press the walls. against the scoring ridges of said mandrel sufficient to score said walls, and severing a ortion of. each folded side edge suflicient to form closing flaps at each endof the. blank.

2. A method of making a seamlessplastic folding c011- tai'ner blank from an. extrudedplastic tube comprising flattening said tube to form folded side. edges, cutting a. blank from said flattened tube, inserting a fiat rigid mandrel having scoring ridges mounted thereonbetween the walls of said blank, applying cutting knives forcibly to each wall of said blank. suflicient to cut said walls along predetermined cutting lines while simultaneously applying, resilient pads against each of said .walls to press the walls against the scoring ridges of said mandrel under sufiicient pressure to score said walls, and severing portions of each folded side edge sufficient to form closing flaps at each end of the blank.

3. The method of claim 2 wherein the cutting knives are driven entirely through the plastic walls of each blank and forcibly against the rigid flat surfaces of the mandrel.

4. The method of claim 2 wherein the plastic blank. is cut and scored at each end thereof to form closing flaps.

5. The method of claim 2 wherein. the scoring pads press each plastic wall against scoring; ridges mounted longitudinally on the mandrel to score. each. of said walls.

. alonga line parallel to and intermediate of the folded ridges of the mandrel. to score the plastic blank.

7. In apparatus for. cutting and. scoring a seamless plasticfolding container. blank, a. flat; rigid" mandrel having. scoring ridges mounted thereon and. a pair of. op.

posing cutting and: scoring dies having cuttingknives-and.

scoring pads mounted thereon. whereinv the lower dieais;

formed with brackets. andistudsfor retainingthe mandrel? -tosaid elements and: a' pair of knifeedges: connecting the outer. side: edges of said" tongue and head elements.

9'. In apparatus for cutting and scoring 'a seamless plastic folding container blank having substantially fiat, oppositely positioned plastic walls, a flat rigid mandrel inserted in said blank and setting and scoring dies disposed adjacent each of said plastic walls, said mandrel and dies having cutting and scoring means disposed along predetermined lines, said mandrel and dies adapted to cooperate under pressure to cut and score foldable end closure elements in said blank along said predetermined lines.

10. The apparatus of claim 9 wherein the cutting and scoring dies have raised cutting knives and scoring pads disposed across the face thereof along the said predetermined lines and the mandrel has scoring ridges disposed across its face adapted to cooperate with said scoring pads.

References Cited in the file of this patent UNITED STATES PATENTS Lysobey June 10. 1952 

1. A METHOD OF MAKING A SEAMLESS PLASTIC FOLDING CONTAINER BLANK FROM AN EXTRUDED PLASTIC TUBE COMPRISING FLATTENING SAID TUBE TO FORM FOLDED SIDE EDGES, CUTTING A BLANK FROM SAID FLATTENED TUBE, INSERTING A FLAT RIGID MANDREL HAVING SCORING RIDGES MOUNTED THEREON BETWEEN THE WALLS OF SAID BLANK, CONTACTING CUTTING KNIVES TO EACH WALL OF SAID BLANK UNDER SUFFICIENT PRESSURE TO CUT COMPLETELY THROUGH SAID WALLS ALONG PREDETERMINED CUTTING LINES, CONTACTING RESILIENT PADS FORCIBLY AGAINST SAID WALLS TO PRESS THE WALLS AGAINST THE SCORING RIDGES OF SAID MANDREL SUFFICIENT TO SCORE SAID WALLS, AND SERVING A PORTION OF EACH FOLDED SIDE EDGE SUFFICIENT TO FORM CLOSING FLAPS AT EACH END OF THE BLANK. 